We need a hair shader like this for Poser ... Shader gurus?



  • Just FYI the strands in dynamic hair are flat single sided polys. Not tubes. (we WERE going there but it didn't get implemented) The lack of depth was causing other problems getting the hair right. One of those problems is you can't do proper SSS on a polygon with no depth. You have to fake it somehow. The other big problem was getting the highlights right. On real hair the highlight takes on a anisotropic look thta follows the strands.

    I pulled out a lot of my own hair trying to get that highlight look. In the end I faked it by creating a wide and narrow highlight. (The super hair shader has specularity and highlight. One wider then the other is my feeble attempt at faking it)
    The other cheat in there is blending some translucence into the hair color. That was my attempt at faking SSS.



  • I'm still hoping for BagginsBill with his latest shaders....

    @ero, does SSS really work for hair? Most hairs I've seen are just made out of strips, there is no "inside"... I would have tried translucence, like Nerd did.



  • cheers guys!

    @bantha said in We need a hair shader like this for Poser ... Shader gurus?:

    I'm still hoping for BagginsBill with his latest shaders....

    @ero, does SSS really work for hair? Most hairs I've seen are just made out of strips, there is no "inside"... I would have tried translucence, like Nerd did.

    Yes SSS still works even though its a strip, in FF at least. Not sure about SF. All those ladies' coups are strips hair. I would advise against translucence since it actually emits light. Hair doesn't emit light... unless you do something funky with it lol. That's the first thing I always kill off with vendor materials.


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    I've been swamped with work, crammed between two vacations. Rather than make you all wait until I am sure I know everything, I'm going to post stuff now.


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    @erogenesis said in We need a hair shader like this for Poser ... Shader gurus?:

    cheers guys!

    @bantha said in We need a hair shader like this for Poser ... Shader gurus?:

    I'm still hoping for BagginsBill with his latest shaders....

    @ero, does SSS really work for hair? Most hairs I've seen are just made out of strips, there is no "inside"... I would have tried translucence, like Nerd did.

    Yes SSS still works even though its a strip, in FF at least. Not sure about SF. All those ladies' coups are strips hair. I would advise against translucence since it actually emits light. Hair doesn't emit light... unless you do something funky with it lol. That's the first thing I always kill off with vendor materials.

    I learned from Stefan that the correct use of FF translucence is NOT by itself. It's not a BSDF like in SF. Rather, it's an input where you plug a Diffuse or Clay node and FF agrees to handle polygon normals differently, so that it will appear to pass light through its interior.

    So back in the day when face-off and I were trying to figure it out, we could have saved a lot of time and misinformation if the Poser team would just WRITE SOME DECENT DOCUMENTATION about this stuff. Sure the vast majority would not understand the engineering, but I do and I could explain it from there. We all wasted a lot of time on this.

    So - the translucence channel "glows" only if you use it wrong. You're not supposed to just plug a texture in. You're supposed to plug a Diffuse node in.


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    I made a twisted ribbon with no thickness, like a giant strand of hair.

    I render in FF, using the PoserSurface built-in diffuse channel, nothing plugged in.
    0_1489492961016_upload-f283a74e-f911-4dc2-a920-5a650e0ecda8

    The bottom and top of the ribbon have normals facing the camera. The middle twist is facing away and since it is lit from "behind" it doesn't light up at all and appears black.


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    If I turn on the "Normals Forward" option (circled in red) then all surfaces are lit even if they are facing away. It's as if they are all facing forward, towards the camera, all the time.

    0_1489493091899_upload-f6072dd4-68c6-4ce4-a465-0e6efecb0d29


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    Now I return to just Diffuse, without Normals Forward enabled.

    I move the light so it is coming from behind the ribbon, shining toward the camera. The ribbon is now "back lit".

    The middle section, which is now facing the light source and was previously black, is now lit. We see the light come through that surface. This is what we all call "translucence" but it's not performed by the translucence channel at all - it's the built-in diffuse behavior.

    0_1489493275419_upload-0d53efae-5b0e-4f60-a31f-348ffdbfbe91

    Meanwhile, the top and bottom of the ribbon are black, since they are receiving light on their "back" sides.


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    Instead of Diffuse, which I turned off, here I try to use Translucence alone. Instead of lighting through the surface it is applying the color uniformly and thus glowing.

    0_1489493423063_upload-959d74d7-8e5e-41bb-a2c6-7efed3c2d03d

    Here I turn off the light and render - we see the uniform glow.
    0_1489493459421_upload-91a22285-0109-4848-89d9-9a2af5ca0e02
    This isn't because the translucence input is broken. It's because I'm using it wrong.


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    This appears to be how you're supposed to use translucence.

    You place a Diffuse node in it, with normals forward checked on that node.

    Now the light coming from "behind" the ribbon is all considered "front side" and light is passing through.

    (I moved the ribbon so Andy's shadow falls on it)

    0_1489493749992_upload-0281505d-2879-4079-900a-f33393cb07e3


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    If I disable the Diffuse node's Normals_Forward, then only the middle section remains lit. That is the section that actually is facing the light source. The others are reversed and remain black.

    0_1489493805212_upload-c07f6e67-237c-47bb-b22c-6aef6ebd85fc

    You can see how confusing this is.


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    Now when I return to front-side lighting (coming from behind the camera) we get another surprise.

    Translucence, when properly assembled, DOES NOT CONTRIBUTE TO FRONT SIDE LIGHTING AT ALL.

    Hmmm.

    0_1489493905728_upload-98fbe5b2-1a08-4bfe-8a2a-70c401b577ab


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    It's overwhelming and confusing to show any more combinations. I'm going to cut to the chase.

    This is the way I've found to get translucence to work right. It's not intuitive.

    0_1489494266637_upload-84c68b10-ac29-46cf-b659-4bd32475c109

    That was front-lit. This is back-lit.
    0_1489494339509_upload-3cd9c350-7e55-432d-b462-55ba640a3856

    You cannot use the builtin diffuse. You have to use TWO Diffuse nodes, and even though they are identical in configuration, you can't share them. One has to be dedicated to Translucence_Color, the other dedicated to Alternate_Diffuse, and both have to have Normals_Forward checked.

    We have four combinations of light setup:

    Normal facing camera and light
    Normal facing camera
    Normal facing light
    Normal not facing either

    I tried lots of other node setups and I always ran into a situation where one of the combinations was black. We want them all lit and this works. If you find another, please show.


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    That was all for FireFly. For SuperFly the rules are different and the above setups do not work the same.



  • @bagginsbill

    Ah! what you say about Translucence makes sense now. I will try it out a.s.a.p... and I am also going to grab a beer and check out the rest of what you wrote.

    Yeah, some documentation would have been nice ;)

    BB, do you have like wiry grey hair standing on end, tiny fogged up glasses on the tip of your nose and bunsen burners and bubbling test tubes stacked dangerously around you? That's the kind of image I sometimes get with your online publications.



  • @bagginsbill Thank you for this, you could have just said, here's how to get Translucence working in FF and most of us would have just bookmarked this. But explaining why you do it the way you do and what happens if you don't is the real bonus!

    Amanda


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    @erogenesis said in We need a hair shader like this for Poser ... Shader gurus?:

    BB, do you have like wiry grey hair standing on end, tiny fogged up glasses on the tip of your nose and bunsen burners and bubbling test tubes stacked dangerously around you?

    Yes. Yes, I do.

    @amethystpendant You're welcome. More is coming. But I have to shovel snow.



  • @bagginsbill
    I always get to be much wiser when I've read your threads. You are a gem (with wiry hair and bunsen burners as Ero says.)
    I'll be looking forward to the next chapter: Superfly (Which I dearly hope to see coming)



  • I had a Black Label beer produced in South Africa, 4 to be precise.

    Upon further inspection of BB's research into the nature of Poser's "translucence" channel, I didn't know if I needed to feel insulted at BB's clear declaration of our staggering ignorance, or that of SM's... :D

    I think one thing is clear though, Einstein ain't got sh|'t on BB. I vote for BB's remains (should that horrible day ever come) to be declared as the type specimen for the human species.

    Damn this black label is good



  • @nerd3d said in We need a hair shader like this for Poser ... Shader gurus?:

    I know this is a bit off topic because it's for strand hair but in the very last update of Poser there's a bunch of new strand hair shaders and a fix for the UV mapping of strand based hair. It was one of the very last things that got in before we all got canned. (Pause to throw another dart at Witless Willy).

    Whoa! Wait! huh???? Geez, how long have I been dead????